Master device, slave device and communication system

Abstract

Master device (1), installed in a vehicle (V) for communicating with one or more slave devices (2, 2a, 2b) installed in the vehicle (V) by switching between a first communication method and a second communication method, the master device (1) comprising: a communication unit (10) that sends a command to the one or more slave devices (2, 2a, 2b) in the first communication method, and that sends a trigger signal to the one or more slave devices (2, 2a, 2b) and receives data sent by the one or more slave devices (2, 2a, 2b) in response to the trigger signal in the second communication method; and a controller (12) that controls the communication unit (10) during the execution of the first communication method to provide negotiation information indicating conditions for the second communication method.to read from a memory (11) and send the negotiation information to one or more slave devices (2, 2a, 2b), wherein, upon termination of the communication which satisfies the conditions after the first communication method has been switched to the second communication method, the controller (12) performs the switch from the second communication method to the first communication method, wherein the negotiation information includes at least one of the following: (i) information indicating the number of transmissions of the trigger signal, (ii) information indicating a time interval between the end of the transmission of the trigger signal and the end of the transmission of a next trigger signal, (iii) information indicating a timing of the transmission of the data, (iv) information indicating a length of the data.

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